Charity is uppermost in the brain

Neuroscientists have found the brain's charity spot: a region that determines whether we put others before ourselves.

A team led by Scott Huettel and Dharol Tankersley of Duke University Medical Centre in North Carolina found that an area at the top and back of the brain is busier in more altruistic people.

"Although understanding the function of this brain region ... may not necessarily identify what drives people like Mother Theresa, it may give clues to the origins of important social behaviours like altruism," said Dr Huettel.

Science has grappled with why people will put the welfare of others ahead of their own, even at personal cost. From an evolutionary viewpoint it makes little sense because it does not increase the chances of someone passing on their genes.

In experiments detailed in Nature Neuroscience today, Dr Tankersley scanned the brains of 45 people using functional magnetic resonance imaging, which allows researchers to watch the brain working in real time. Volunteers either played a computer game or watched a computer play one by itself. In either case, winning earned money for a charity.

Volunteers were also asked about their behaviour, in particular how they treat others and how often they put others before themselves. During the experiment the most charitable people showed the most activity in the posterior superior temporal sulcus, which is normally linked to processing incoming information, sorting out social relationships and controlling movement.

Brain activity was higher when volunteers watched the computer play the game than when they played themselves. The researchers suggest altruistic behaviour comes from the way people view the world rather than how they behave themselves, and knowing the computer was earning money for charity made it easier to imagine an intentional "mind" behind the screen, apparently turning the game into a social situation involving altruism.